Distinguishing features: Conical discoasteralids with a concave base, consisting of a mass of elements radiating from a common origin.

Morphology remarks: See genus Sphenolithus for discussion. Evolution & Phylogeny: Sphenoliths first appear in the Palaeocene and go extinct in the mid Pliocene. They show some similarities to Fasciculithaceae and are thought to have similar origins.

Geological Range: Last occurrence (top): near base of Piacenzian Stage (14% up, 3.5Ma, in Piacenzian stage). Data source: Total of range of species in this databaseFirst occurrence (base): near top of Danian Stage (90% up, 62.1Ma, in Danian stage). Data source: Total of range of species in this database